Microwave tomography of lossy objects from monostatic measurements

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This paper addresses the problem of microwave tomographic imaging of dielectric objects. We first recall the Fourier relationship between Born approximation far-field cattering and the complex permittivity of a lossy scatterer illuminated by a plane-wave uniform radiation, and describe a monostatic multifrequency measurement system. We then propose a data preprocessing strategy, which permits a projected Landweber tomographic reconstruction scheme to be applied. It is assumed that the object under test has a finite extent, and its permittivity is not a function of the frequency of the probing radiation. The complex permittivity of a lossy object is always frequency dependent, but if our hypotheses are verified the proposed preprocessing can eliminate this dependence, thus making our multifrequency measurements suitable for simultaneous exploitation. Finally, we outline the reconstruction technique and show the results of some simulated experiments. We also show that the Landweber method can be applied to measurements on lossy as well as lossless materials, except for cases of limited-angle data, where in the lossy case more restrictive conditions are to be met.